The present invention relates to a burning apparatus and a method for manufacturing reduced iron using the same, and more particularly, to a burning apparatus and a method for manufacturing reduced iron using the same capable of improving a metallization rate of reduced iron though control over a temperature and an oxygen concentration inside a burning furnace.
A typical reduced iron manufacturing apparatus includes a plurality of hoppers accommodating an iron raw material and a carbonaceous material, respectively, a crusher receiving and crushing each of the iron raw material and the carbonaceous material, a mixer receiving and mixing the iron raw material and the carbonaceous material, a molding machine compressing and molding the resultant mixture obtained in the mixer, and a burning furnace heat-treating and burning a coal briquette molded in the molding machine.
Meanwhile, the coal briquette is heat-treated and reduced in the burning furnace to thus manufacture reduced iron. For this purpose, the burning furnace is commonly sealed, and a carbon monoxide (CO) gas, a carbon dioxide (CO2) gas or a hydrogen (H) gas is supplied to the burning furnace in order to induce a reducing atmosphere inside the burning furnace.
However, it takes much time to create a reducing atmosphere inside the burning furnace, and thus there is a problem in which mass production of reduced iron is difficult.
Approximately 60% of an iron production amount throughout all over the world is manufactured through a blast furnace method which has been developed since the 14th century. The blast furnace method is a method in which both iron ore experiencing a sintering process and coke manufactured by using flaming coal as a raw material are introduced into a blast furnace, and high-temperature air is blown into the blast furnace to reduce the iron ore into iron, thus manufacturing ingot iron.
Since the blast furnace occupying the majority of an ingot iron manufacturing equipment requires a raw material having a predetermined level or more of strength and having a grain size for securing air permeability in the blast furnace due to its reaction characteristic, the blast furnace depends on coke manufactured by processing specific coking coal as a carbon source that is used as a raw material and a reductant as described above, and mainly depends on a sintered ore experiencing a series of agglomeration processes as an iron source.
In order to smoothen a flow of a reduction gas, a sintered ore formed by making a fine iron ore in a lump shape and coke formed by drying and distilling fine coal to make the fine coal in a lump shape are charged into a blast furnace.
Since the sintered ore having a lump shape has an extremely small contact area per unit volume with a raw gas compared to the fine iron ore, and the sintered ore has a small contact area with carbon even after reduction is completed in the blast furnace, it is difficult for carbon to permeate into reduced iron. Therefore, since the sintered ore has a high melting temperature, the sintered ore has fundamental problems in that a great amount of energy is consumed for melting the sintered ore and a production rate of molten iron is slow.
Therefore, developed was a process in which ultrafine iron ore is agglomerated into a briquette or a pellet, and a reducing atmosphere is induced in a rotary hearth furnace (RHF) to directly manufacture reduced iron. However, the process of directly manufacturing the reduced iron shows annual production of approximately 150,000 ton to 500,000, and thus has a limitation in mass production. Also this process has a reduction rate of 95% or more, and thus the reduced iron obtained by this process is used as a raw material for an electric furnace.
Also, developed was another process in which ultrafine iron ore is agglomerated into a briquette or a pellet and then burnt at a temperature of maximum 1,350° C. to partially manufacture reduced iron, and by which mass production is possible in an annual production of maximum 4,000,000 tons. However, since such a process is performed in an open type burning furnace that is not sealed, it is difficult to control a temperature and an oxygen concentration inside the burning furnace, and thus there is a problem in a metallization rate of partially reduced iron being relatively low.